Clive Davis has come out as bisexual. The 80-year-old music mogul revealed his sexuality in a new memoir, saying that following half a century of relationships with women, he is now the long-term partner of another man.

Although "coming-out" stories have become more common in the music business, Davis is noteworthy as one of the industry's best-known executives – a quintessential old white guy. Davis has steered labels such as Columbia, Arista, BMG and Sony since the late 60s, signing artists such as Janis Joplin, Bruce Springsteen, Notorious BIG and Kelly Clarkson. He was inducted into the Rock and Roll Hall of Fame in 2000.

In his new book, The Soundtrack of My Life, Davis recalls that his first time having sex with a man was during "the era of Studio 54", when he was married to his second wife, Janet Adelberg. "On this night, after imbibing enough alcohol, I was open to responding to his sexual overtures," Davis wrote. "Was I nervous? Absolutely. Did the heavens open up? No. But it was satisfying." The experience prompted a period of "soul searching and self-analysis", and after separating from Adelberg in 1985 Davis dated partners of both sexes. Since 1990, both of his long-term relationships have been with men.

"You don't have to be only one thing or another," Davis said in an interview with US chat show host Katie Couric. "I opened myself up to the possibility that I could have a relationship with a man as well as the two that I had with a woman." In another chat, with Nightline, Davis complained that bisexuality is "maligned and misunderstood". "For over 50 years I never had sex with a male," he said. "It wasn't repressed. I had very good sexual relationships with women."

Davis admitted that his evolving sexuality had been a "tough adjustment" for one of his sons, the concert promoter Mitch Davis. But after "one very trying year", the two men are once again on good terms.

Elsewhere in The Soundtrack of My Life, Davis described the hardship of watching Whitney Houston struggle with addiction. "When I saw you last night at the Michael Jackson concert, I gasped," he wrote to her in 2001. "When I got home I cried. My dear, dear Whitney." But the singer resisted an attempted intervention. "She was in complete denial," Davis wrote. "If an addict does not want to get help, there ultimately is very little that anyone else can do."